The business systems that provide various services using enterprise IT architecture may involve complex and numerous stages. These business systems may need to handle various scenarios, such as changing the service contract for the end users, offering new service contracts for new customers, upgrading old services to new services in a non-stop mode, and keeping the older services for some existing customers. Furthermore, IT service providers may want to provide several versions of services in parallel, and offer specific variants to certain customers. Additionally, some services requesters may want to access different versions of services in a uniform manner or even switch between the different versions of services at runtime, while the others may not want to explicitly deal with the different service versions. This is the general area that embodiments of the invention are intended to address.